Genetic Variation Analysis Of Main Fatty Acids In Seeds Of The New-type Brassica Napus

Brassica napus(A~nA~nC~nC~n,2n=38)is an important source of cooking oil in the world,and also possesses important value for industrial oil and future bioenergy development.The fatty acid composition in B.napus is closely related to its diverse oil uses.Cultivating new rapeseed resources with rich fatty acid composition variation,and elucidating its genetic basis would be of great importance to rapeseed fatty acid improvement and the development of rapeseed special oil.In this study,the fatty acid phenotype was investigated and analyzed in a multi-generation resynthesized new-type B.napus recurrent selection population,and lines with diverse fatty acid variations were seleceted.Furthermore,fatty acid related QTL mapping,integrating and comparison was performed in three parental genetic mapping populations(HS DH,NS DH and TS DH)which is developed by crossing new-type and normal B.napus accessions,with a view to providing new breeding and genetic resources for rapeseed fatty acid modification and specific oil development.The main results are as follows:1.Using the seed fatty acid data obtained from 10 rounds(S1～S10)selection of the new-type B.napus recurrent selection population for analysis,it is found that the oleic acid content has been significantly increased.The average oleic acid content of S9 sterile lines and S10 fertile lines reached the highest,which were 67.12%and 64.21%,respectively.The content of linoleic acid gradually decreased following multiple selection rounds,of which the average content of sterile lines decreased from 20.8%to 18.19%and that of fertile lines decreased from 21.14%to 18.62%.However,the content of linolenic acid was relatively stable and did not change significantly following multiple selection rounds.Continuous self-purification of some of the above strains,screening to obtain 123 parts of high oleic acid(>68%),816 parts of high linoleic acid(>20%),178 parts of high linolenic acid(>12%)and high oil content 467 copies(>45%).2.Analyze the phenotype and QTL mapping of the main fatty acid components of seeds on the three DH populations created by using the new pure Brassica napus line as the hybrid parent.A total of 57 QTLs were identified in the HS DH population,mainly located on chromosomes A01,A02,A03,A09 and C05.The major sites of oleic acid and linoleic acid are co-located on the C05 chromosome;the major sites of linoleic acid are located on the A09 chromosome.A total of 68 QTLs were identified in the NS DH population,mainly located on chromosomes A02,A08,A10,C03 and C06.Among them,the major sites of erucic acid,oleic acid and linoleic acid are located on the A08chromosome;the major sites of linolenic acid are located on the A02 chromosome.A total of 25 QTLs were detected in the TS DH population.Only the major QTL for oil content was detected on the A05 chromosome,and the rest were minor QTLs with no overlap and smaller effects.There is no overlap between the 3 mapping populations and the TN DH population.Compared with the sites detected in other conventional Brassica napus,the major sites of oleic acid and linoleic acid detected on the C05chromosome of the HS DH population are new sites;the erucic acid,oleic acid and linoleic acid of the NS DH population The major sites of oleic acid detected on A08chromosome overlap with the reported sites.